Page 12 - Hensler Surgical - PAPR by Bullard System - 2020

required to maintain a positive pressure in the respiratory-inlet covering.” At the time,
the OSHA regulations indicated that PP devices could achieve APF’s of 1000.
Therefore, for the 77 and 88 respirators to be assigned a PF of 1000, OSHA wanted proof
that they were in fact PP devices, even though they were loose-fitting helmet/hood-style
respirators.

Bullard worked with OSHA and Lawrence Livermore National Laboratories (LLNL) to
develop the requisite testing protocols for the 77 and 88. Ultimately, OSHA accepted
Bullard’s test protocols for defining PP.

As a result of the study LLNL performed on Bullard’s Models 77 and 88 respirators in
1995, OSHA granted these respirators an APF of 1000 regarding the Lead in
Construction standard. By doing this, OSHA placed itself in the position of being a de
facto certifying agency for respirators, a position neither it nor NIOSH desired, but found
necessary in the absence of an updated APF ruling.

With this new August 2006 rule, it is OSHA’s intent to get out of the “letter writing” and
de facto respirator certification business. With specific regard to footnote 4, the new
ruling now clearly places the responsibility for proper respirator selection on employers
(page 50168). It is now the employer’s responsibility to evaluate and interpret the
respirator manufacturer’s evidence and make respirator selection decisions accordingly.

The LLNL study subsequently became the prototype for the ORC study, published in the
Journal of the American Industrial Hygiene Association in 2001. This work was also
carried out by LLNL. Like the Bullard study, pressure within the respiratory inlet
coverings was measured, recorded and analyzed.

One of the conclusions of the ORC study was that there is no correlation between
respirator performance, as reflected by its Protection Factor rating, and positive pressure
measured inside the respirator inlet covering (hood/helmet). Therefore, in the new
OSHA APF regulation, PAPR’s and SAR’s are no longer necessarily required to be
positive pressure devices in order to be classified with an APF of 1000. As stated on
page 50167, “This study indicates that pressure within the respiratory inlet covering is
only one of a complex set of factors that determine the protection provided by PAPRs
and supplied-air respirators, and should not be considered by itself.”

In its Final Rule, OSHA removed from footnote 4 the language that appeared in the
original proposed rule which stated that only helmet/hood respirators that ensure the
maintenance of positive pressure shall receive an APF of 1000 (page 50168).

The LLNL and ORC studies, as well as those performed in Bullard’s laboratory and other
similar facilities such as the U.S. Army’s Research, Development and Engineering
Command (RDECOM) facility in Aberdeen Proving Ground, MD, were/are performed
using aerosol detection photometers and generated liquid aerosols of known and
controlled concentration high enough to be able to measure elevated PFs.

Powered Air Purifying and Supplied Air Respirator Performance Page 5
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